The present invention relates to a mechanism for attaching a component to an instrument having variable geometry. More particularly, certain embodiments of the present invention relate to a universal attachment mechanism for attaching a surgical tracking device to a surgical instrument.
During surgical operations, it is beneficial to be able to track the direction and progress of a surgical instrument, such as a drill bit, into a patient's body in order to ensure that the instrument is directed into the appropriate point in the body. Therefore, surgical tracking systems have been developed that are able to display and monitor movement of a surgical instrument relative to an image of the patient's body.
One system used for surgical tracking is an electromagnetic tracking system. In a typical electromagnetic tracking system, the area of the patient's body where surgery is to take place is imaged using an imaging technology such as the MRI, X-ray, CT scan or any other appropriate imaging device. The scanned images are stored in a computer system and are displayed on a screen during the surgical procedure. A transmitter that emits an electromagnetic field is then secured to the patient's body proximate the area of the patient's body where surgery is to take place. The instrument that is to be tracked during surgery has a receiver attached thereto that receives the electromagnetic signals from the transmitter. The transmitter and receiver are both connected to the computer that displays the image. The computer translates the location of the transmitter on the patient's body to an equivalent point on the image. Then, by monitoring the signals sent from the transmitter to the receiver as the instrument is used in surgery, the computer is able to track the movement of the instrument relative to the transmitter and transpose the movement to the image. Therefore, medical personnel may closely track the positioning and progress of the instrument within the patient's body during surgery by examining the image.
Alternatively, in some electromagnetic systems, a receiver is placed on the patient and the instrument, and a field transmitter is placed proximate the patient. The receivers and transmitter are connected to the computer, and the computer is then able to track the movements of the instrument on an image similarly to the system using just a single receiver.
There are other surgical tracking systems besides electromagnetic tracking systems, such as optical tracking systems. Optical tracking systems typically use light emitting diodes (LEDs) that are attached to the surgical instrument and to the body portion of the patient on which the surgical procedure is to be performed. The LEDs are tracked by a camera unit (sometimes referred to as a digitizer). The output of the camera unit is used by the computer to recreate the movement of the instrument on the image.
In order for a surgical tracking system to work, the tracking device attached to the instrument, whether it be a receiver, transmitter or an LED, must be secured against movement relative to the instrument. If the tracking device moves relative to the instrument during surgery, the recreation of the instrument's position on the image will be incorrect. An incorrect tracking image may cause a surgeon to misdirect the instrument and possibly endanger the patient's health.
Since most surgical instruments are not provided with an integral tracking device, a separate attachment mechanism is generally used to retain a tracking device to the instrument. Many surgical instruments, such as drills, have traditionally been cylindrical in shape. As a result, a tracking device was often connected to the instrument by a cylindrical clamping mechanism, for example two C-shaped pieces connected at one by a hinge and at another end by a clasp. However, as ergonomic concerns have become increasingly prevalent in instrument design, the instruments have assumed more complex and contoured shapes. Many surgical instruments made today have a complex and variable geometry that cannot be accommodated by attachment mechanisms of such limited versatility as a conventional cylindrical clamp. Therefore, attachment mechanisms are often custom-made for each different kind of surgical instrument. In one common design, a boss is specifically developed for attachment to each surgical instrument, and the tracking device is then secured to the boss.
The practice of custom making surgical tracking attachment mechanisms has several drawbacks. First, the companies that make the attachment mechanisms must custom-design, develop, and market a new attachment mechanism specifically for each new surgical instrument that comes into the market. Thus, a company making attachment mechanisms must devote a significant amount of time and money to keeping up with new designs by the instrument makers. Companies that make the attachment mechanisms may, of course, work closely with the companies that make the surgical instruments in order that the instruments and the attachment mechanisms are compatible when the instruments come to market. However, this obligatory collaboration greatly slows down development and product-to-market time of the surgical instruments. Also, the companies that make the attachment mechanisms may be tied into different contracts with certain instrument makers and may be limited from making inroads into business with other instrument makers. An inability to fully reach into the instrument market is especially frustrating because recently there has been a significant increase in the number of new surgical applications, especially in orthopedics. Furthermore, even in instances where the same company makes the instrument and the attachment mechanism, the company must still invest the time and money into custom-designing and developing a new attachment mechanism for each surgical instrument, and therefore still has a delayed product-to-market time. Additionally, because of collaboration between instrument makers and attachment makers or instances where the same company makes the instrument, attachment mechanism, and tracking system, the end user may be limited to only using the tracking system of the company that makes the attachment mechanism for a particular instrument.
Therefore, a need exists for an improved attachment mechanism compatible for use with as many different instruments and tools as possible.